[autotest] Modify metadata_reporter to handle upload failure better

1. reduce the max failure time to 10min. After that, all uploads are limited
   to 10 entries.
2. After an upload succeeds, double the number of entries in the next upload,
   still caps at 50k. This is to avoid the case that a small number of entries
   can be uploaded, but failed at large amount.

BUG=None
TEST=local run

Change-Id: I7d76da9958e5f2cc021cef20606bc3b86e9bcf48
Reviewed-on: https://chromium-review.googlesource.com/294319
Trybot-Ready: Dan Shi <dshi@chromium.org>
Tested-by: Dan Shi <dshi@chromium.org>
Reviewed-by: Fang Deng <fdeng@chromium.org>
Commit-Queue: Dan Shi <dshi@chromium.org>
1 file changed